Episodic and diurnal variations of unconjugated plasma estriol (E3) levels will be assessed in: a) hospitalized women with uncomplicated pregnancies, b) hospitalized diabetic patients at 36 to 39 weeks' gestation and c) outpatients with uncomplicated term pregnancies. In groups a) and b), venous blood will be sampled hourly for 24 hours and in group c) blood will be drawn 7 times over a 1 hour period at 2 separate occasions under different conditions. The value of total and unconjugated plasma estriol (E3) will be assessed in pregnancies complicated by hypertensive disorders and/or intrauterine growth retardation. Plasma E3 will be measured daily in hospitalized and twice weekly in ambulatory patients who will be followed with antepartum fetal heart rate testing. The value of serial unconjugated plasma estriol assays in the management of presumably prolonged gestation in patients with unreliable due dates will be determined. A radioimmunoassay for oxytocinase, and enzyme produced by the trophoblast, will be established. It will be evaluated whether this assay may serve as a pregnancy test, an indicator of placental size and function or a test for the presence of trophoblastic tissue in moles and choriocarcinoma and whether unusual serum levels of this enzyme may be associated with abnormal uterine contractility.